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Neurovascular evidence for a co-occurrence of teeth and baleen in an Oligocene mysticete and the transition to filter-feeding in baleen whales
Zoological Journal of the Linnean Society ( IF 2.8 ) Pub Date : 2021-03-06 , DOI: 10.1093/zoolinnean/zlab017
Eric G Ekdale 1, 2 , Thomas A Deméré 2
Affiliation  

Extant baleen whales (Mysticeti) have a deciduous foetal dentition, but are edentulous at birth. Fossils reveal that the earliest mysticetes possessed an adult dentition. Aetiocetids, a diverse clade of Oligocene toothed mysticetes, have a series of small palatal foramina and associated sulci medial to the postcanine dentition. The openings have been homologized with lateral palatal foramina that transmit neurovascular structures to baleen in extant mysticetes, thereby implying a co-occurrence of teeth and baleen in aetiocetids. However, homology of the foramina and sulci have been questioned. Using CT-imaging, we report that the lateral palatal foramina of Aetiocetus weltoni are connected internally to the superior alveolar canal, which transmits neurovascular structures to baleen in extant mysticetes and to teeth in extant odontocetes. Furthermore, the lateral palatal foramina of Aetiocetus are separate from the more medially positioned canals for the greater palatine arterial system. These results provide critical evidence to support the hypothesis that the superior alveolar neurovasculature was co-opted in aetiocetids and later diverging mysticetes to serve a new function associated with baleen. We evaluate competing hypotheses for the transition from teeth to baleen, and explore the transition from raptorial feeding in early mysticetes to filter-feeding in extant species.

中文翻译:

渐新世神秘动物中牙齿和鲸须同时出现的神经血管证据以及须鲸向过滤摄食的过渡

现存的须鲸(Mysticeti)有一个乳牙胎,但在出生时是无牙的。化石表明,最早的神秘动物拥有成年牙列。Aetiocetids 是渐新世带齿的神秘动物的多样化进化枝,具有一系列小的腭孔和相关的后牙列内侧沟。这些开口已与侧腭孔同源,后者将神经血管结构传递到现存神秘动物中的鲸须,从而暗示牙齿和鲸须在甲壳纲中同时出现。然而,孔和脑沟的同源性受到质疑。使用 CT 成像,我们报告 Aetiocetus weltoni 的侧腭孔在内部连接到上牙槽管,上牙槽管将神经血管结构传输到现存的 mysticetes 的鲸须和现存的齿鲸的牙齿。此外,Aetiocetus 的外侧腭孔与更大的腭动脉系统的更靠内侧的管分开。这些结果提供了重要的证据来支持这样的假设,即上肺泡神经脉管系统被增选在 aetiocetids 和后来发散的 mysticetes 以服务于与鲸须相关的新功能。我们评估了从牙齿到鲸须过渡的竞争假设,并探索了从早期神秘动物的猛禽摄食到现存物种的过滤摄食的过渡。这些结果提供了重要的证据来支持这样的假设,即上肺泡神经脉管系统被增选在 aetiocetids 和后来发散的 mysticetes 以服务于与鲸须相关的新功能。我们评估了从牙齿到鲸须过渡的竞争假设,并探索了从早期神秘动物的猛禽摄食到现存物种的过滤摄食的过渡。这些结果提供了重要的证据来支持这样的假设,即上肺泡神经脉管系统被增选在 aetiocetids 和后来发散的 mysticetes 以服务于与鲸须相关的新功能。我们评估了从牙齿到鲸须过渡的竞争假设,并探索了从早期神秘动物的猛禽摄食到现存物种的过滤摄食的过渡。
更新日期:2021-03-06
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